How to bleed air out of boiler

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Old 10-09-12, 06:07 PM
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Question How to bleed air out of boiler

Hello,

I've cruised this forum many times but first time posting. I also bought my first house this year and have a question about bleeding the air from my hot water system. Here are the symptoms:

The house is a 2-story cape and was built in 2002. When the heat does come on, it sounds like there's a running brook going through the house (I checked for leaks, no problems anywhere). I hear constant water "whooshing" sounds, like the air is being pushed around in the pipes as the hot water moves.

I checked the baseboard heaters and there are no bleed valves, only solid elbows. From what I've been reading, I should be able to bleed the air from the boiler itself but I'm not sure where to begin. I have a short hose that I can use and a few 5 gallon pales to catch the water and watch for air bubbles. My main question is what valves should I open and/or close to properly bleed the system? The home uses a Laars Newport oil fired boiler (NP-85) with two zones.

Attached are a couple pictures showing the setup. If you need additional pictures or information, please let me know. Any advice would be much appreciated. The heat is working and house is plenty warm but I'm sure air in the system can't be a good thing. Thank you for your time.

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Old 10-09-12, 07:09 PM
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My only wish is for bigger pics... can't really focus this late at night!

I believe that the forum resizes these when you upload from computer. If these were originally larger, would it be possible to load them to photobucket.com so we can view full size?

Yes, you definitely have air in the system.

See that pressure and temp gauge on the front of the boiler? Read that and tell us what it says... or take a close up pic. ( hint: use the MACRO feature on camera if you can't get it to focus close)
 
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Old 10-09-12, 07:29 PM
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I'd still like bigger pics... but I put on a pair of stronger glasses and see that you do have the proper valves to do a 'purge' of the system.

Before we do that though, I want to ask a question or three...

I do not see any means of automatic air collection and venting. It might be there, I just don't see it.

Is there anything that looks like this:


image courtesy pexsupply.com

or this:


image courtesy dekkasupply.com

or this:



on the system anywhere?

If not, your installers left out a vital piece of the puzzle.

Next, I would like to mention the way the gray expansion tank is mounted. Not IF, but WHEN the rubber bladder inside that tank fails, it will fill with water and get heavy. This will put a LOT of torque stress on the connection point... not good.

Those tanks should not be mounted sideways, they should be hanging from the piping like this:



They will WORK in other positions but will not last as long.

I know you won't be moving it anytime soon, so at the very least, give it some support! Pick up a roll of that galvanized steel strapping with the holes in it and put a nail or screw in a joist above and run the strapping down, under the tank and back up again. You don't want to pull it up, only snug to support the weight.
 
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Old 10-09-12, 07:32 PM
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One more thing...

What does the label on that 'flapper valve' ( barometric damper ) on the exhaust pipe say? make/model?

Something looks weird about that...
 
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Old 10-10-12, 05:25 AM
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What are the green components just above the two circulation pumps?
 
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Old 10-10-12, 06:16 AM
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The bleed

The green things look like flow valves. Mostly you bleed air from the highest part of the system, unless air is trapped in dropped loops in the system. Draining water from the boiler won't get rid any air, and will draw in air. Hopefully there are air vents on the higher baseboards, or rads on your system.
Sid
 
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Old 10-10-12, 06:29 AM
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Thank you all for the feedback, I sincerely appreciate it.

I apologize for the small pictures; the forum did resize them. Below are more larger pictures to view from Photobucket.

In response to some of your comments...

NJ Trooper: Thank you for the tip on supporting the expansion tank! That makes complete sense and I will certainly do that. I'm also including some photos for you to show the Taco air separator and other parts you mentioned. Regarding the pressure gauge, it did read 10psi for water pressure but I tried draining some of the water from one of the zones (about 2 gallons) and then when I checked the gauge again, it read zero. It hasn't increased pressure since.

Northern Mike: I'm not sure, but they look like they have some sort of screw top (like the caps on a car tire's valve stem, except larger). Could these also be to let air out?

Sidny: I checked all baseboard heaters in the house, no bleed valves on any of them.

Thanks again for the help, everyone.

http://i1282.photobucket.com/albums/...ps7e4b97cd.jpg

http://i1282.photobucket.com/albums/...psa2619e43.jpg

http://i1282.photobucket.com/albums/...ps5134e805.jpg

http://i1282.photobucket.com/albums/...ps555c1114.jpg

http://i1282.photobucket.com/albums/...psf6c7a143.jpg

http://i1282.photobucket.com/albums/...ps0ee98423.jpg

http://i1282.photobucket.com/albums/...ps5ed84bfb.jpg

http://i1282.photobucket.com/albums/...pscbf1c344.jpg

http://i1282.photobucket.com/albums/...psa119fb8a.jpg
 
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Old 10-10-12, 06:46 AM
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Are those two blue valves to the right in pic #1 open?

This are the valves at the feed. You need to get pressure before you do anything else.
 
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Old 10-10-12, 06:52 AM
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The first middle valve (3rd from the left if you're looking at all the blue valves) feels open but the 4th (last one on the right) is closed. If I open the one on the far right, isn't water going to pour out of the drain pipe below it? Look at the 2nd photo to see what I'm talking about.

Thanks for the reply!
 
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Old 10-10-12, 07:01 AM
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These two............................
 
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Old 10-10-12, 07:03 AM
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Yes, those are the valves I was referring to. Left one open, right one closed. When I open the right one, water spills onto the floor via the drain tube below it (see 2nd pic).
 
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Old 10-10-12, 07:11 AM
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This tube?.............................
 
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Old 10-10-12, 07:16 AM
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Yes. I opened the blue valve above it for a few seconds and water started pouring onto the floor out of that tube, so I shut the valve again (which is the way it was when I bought the house).
 
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Old 10-10-12, 07:18 AM
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Make sure this handle is screwed all the way on. Then lift that lever vertical. Put a bucket under that tube and open the blue valve. The boiler should start filling and the leak should stop out of that tube.. Fill the boiler to about 15 psi. Watch the gauge. When you get near 15 psi lower that lever.

Let me know how you do.
 
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Old 10-10-12, 07:32 AM
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Ok, here are the steps I took:

1. Lift the little lever on top of the water feed regulator so that the lever was vertical.
2. Put a bucket under the drain tube and opened the far right blue valve.
3. Waited about 3 minutes. Only small amount of water came out of drain tube and boiler water pressure increased to 15 psi.
4. Dropped the regulator lever back to normal position, closed the far right blue valve again.

Do these steps sound correct? Should I have left the far right blue valve on (open) permanently? Thank you.
 
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Old 10-10-12, 07:48 AM
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Do these steps sound correct? Should I have left the far right blue valve on (open) permanently? Thank you.

Yes you should leave the blue valve open IMO. But if water continues to leak out that tube then close the blue valve. You will need to replace that device which is a backflow preventer.


OK now make sure this cap on the top here is loose. ( pic below) If water come out let me know. Let me know if it was tight or loose already. If it leaks you can uncrew the cap and push in the shrader valve to try to clear it. You will get a spray of water. Have a towel handy

The cap should be left loose. But if it continues to leak and will need to be replaced before you fire the boiler.



http://i1282.photobucket.com/albums/...ps5ed84bfb.jpg


Fire up the system if it did not leak.. That air vent should remove the air as each zone is circulated. Run one zone at a time.

Note the pressure and temp when the boiler gets at its hottest and kicks off.

Let me know how it goes and any concerns you see.
 
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Old 10-10-12, 08:09 AM
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Ok, I tried keeping the far right blue valve (one above backflow preventer) open all the time but there was a small trickle that continually flowed out of the drain pipe. Is it absolutely necessary to keep this blue valve open all the time?

Regarding the cap on top of the Taco air separator, it was screwed on tight. I tried unscrewing it very slowly and the more I loosened it, the more water came out the top. I had to screw it on tight again to keep water from spilling onto the boiler. I believe the boiler was on while I was attempting this. Should it be off? Do these symptoms sound like I need a new air separator?
 
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Old 10-10-12, 08:40 AM
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Is it absolutely necessary to keep this blue valve open all the time?
No you can keep it closed. If the boiler should lose water you will need to feed it manually. Do not feed water to a hot boiler. 15 psi is what you want cold. As the boiler heats up the PSI will increase some. Never over 30psi.

I had to screw it on tight again to keep water from spilling onto the boiler.

I would just replace it. Shut the boiler down and let it cook. Go to the home store and get a new airvent.



Bothe home stors have these parts.

You can get a new one of these. Easy to change. make sure same brand.

Shop Watts 1/2 IN Dual Check Vacuum Breaker at Lowes.com

Although they show this vent they have different syles. Get one like you have and not this one.

Shop Watts 1/8 IN Automatic Vent Valve at Lowes.com




Then we can guide you through.


get a roll of teflon tape also.






 
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Old 10-10-12, 08:51 AM
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Sounds good. Thank you very much for the help. I will plan on buying a new air separator and vacuum breaker this weekend.

In the meantime, is there a way I can manually bleed the air out of the system?
 
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Old 10-10-12, 09:00 AM
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In the meantime, is there a way I can manually bleed the air out of the system?
You may make things worse doing that.

You could try unscrewing the cap on the air vent and pushing the schrader valve in to clear it. Get a towel and do it cool so you do not get burnt by hot water. But I think once they start leaking they are shot. So without that you will not get all the air out. Adding more make up water to the boiler adds more air.


You need to relive the pressure to change it. It unscrews from the air seperator.


 
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Old 10-10-12, 09:07 AM
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Also when you do change that air vent and relieve the pressure off the boiler you will want to check the pressure in that expansion tank. Use a tire gauge to check. That blue cap unscrews and there is a valve there. Should be 12-15 psi.

Use a bike pump to add if needed.

When you do relieve the pressure you want to close off valves to the zones so you lose as less water as possible.
 
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Old 10-10-12, 10:23 AM
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I won't worry about bleeding the air for now then, not until the parts are fixed.

One more quick question: To unscrew the air vent cap and try to clear it, all I need to do is make sure boiler is off for a while to cool the water and close the zone valves, is that correct? I'd like to try and clean that out first and see if I can get the current air separator working again since money is tight. I did notice a lot of mineral buildup on the air vent cap itself and am hoping I might be able to unclog it.
 
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Old 10-10-12, 10:35 AM
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Don't unscrew the whole vent. Just the cap on top. There is a air valve under there like a bike tire.

Just push it in a few times. You will just get a spray out. possibly the leak will stop and it may start purging air.

But I think its shot. When you replace you need to relive pressure from the boiler and let it cool. And close all the zones. Then that whole vent unscrews.

But I need to see where that is in relation to the valves. I will go and review the pictures. It may be on the system side of the valves.

In the meantime you should have heat although noisy.
 
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Old 10-10-12, 11:19 AM
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I gave it a try, unscrewed the cap only, then pushed in the valve a few times. I did get a spray like you said and it continued to leak after that, so time to replace. Is the vent on top of the air separator replaceable, or do I need a whole new Taco air separator unit?

Thanks again for all the help.
 
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Old 10-10-12, 11:33 AM
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It unscrews from the air seperator.

Auto Vent 670 - Chicago, Illinois - Maid-O'-Mist
 
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Old 10-10-12, 12:19 PM
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Perfect, thank you. I'll let you know how it goes after I replace the parts.
 
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Old 10-10-12, 03:30 PM
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While you've got the system pressured down for the maintenance, it would be an excellent time to check and charge that expansion tank... in case nobody has mentioned this yet.

Read this:

http://www.doityourself.com/forum/bo...sion-tank.html

There's step by step instruction for doing so...
 
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Old 10-10-12, 04:52 PM
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Certainly good advice, I will plan on doing this as well as adding the support strap. Thank you.
 
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Old 10-15-12, 01:02 PM
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Ok, I have the new part in hand. I ended up buying a whole Taco VRTX125-3 because the price compared to buying the vent alone wasn't that different. I do have a couple questions:

  1. If possible, I'd like to not have to unscrew the old Taco main body from the current plumbing. It looks like a tight fit and I'd rather keep the body in place but replace the unit's internals and vent. I know the vent is replaceable and unscrews from the top, but how can I also replace the rest of the unit's internals? Is that even needed or should I only worry about replacing the vent?
  2. As far as putting the new Taco part(s) in place, I'm assuming all I need to do is shut off the boiler for a while to get the water temp down, close the zone valves, then start unscrewing the Taco vent and have a towel ready to catch the water. Does this sound correct or am I missing any steps?

Thanks again for all the help, everyone.
 
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Old 10-15-12, 01:48 PM
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Hmmm. You spent over $100 on a whole unit?

The vents are $20 or less if you shop around.

Amazon.com: Taco 400-4 1/8-Inch-NPT Float Air Hy-Vent: Home Improvement


But anyway I believe the top unscrews and you can swap out the cartridge. I believe its just a type of screen and acts like an air scrubber. Probably a good idea since you have it already. It un-screws from the body.

http://www.taco-hvac.com/uploads/Fil...ry/102-071.pdf


Make sure you remove the pressure off the boiler and that it is cool.


Also there is a tapping on the bottom for the expansion tank. Possible its a good time to move it. I believe its the preferred location. You would simple plug the place where the expansion tank is now.
 
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Old 10-15-12, 01:59 PM
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I have a different vent, it's about $80 at most places I could find it: 419-1 - Taco 419-1 - 1/2" x 3/4" High Pressure Vent. I paid $90 for the whole unit.

I'll try the replacement this evening after the boiler temp and pressure are down, will let you know how it goes.

Good point about the expansion tank. I will check if there's room, I think it's tight under the air separator and that's why the original plumber put it on the side.

Thanks.
 
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Old 10-15-12, 02:14 PM
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Hmmm its a high pressure air vent.....? I did not do my homework and am not familiar. I am wondering why they used this ?

What does the new vent say on the top? You do not need the high pressure one. I looked at your pics abnd yours says 150psi.

I did find it for $31, but probably irrelevant.

418-4 - Taco 418-4 - 1/2" FNPT x 3/4" MNPT Hy-Vent
 
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Old 10-15-12, 02:35 PM
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I believe that the Maid-0-Mist No. 75 is also a direct replacement for that float vent. about $25 or so.
 
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Old 10-16-12, 06:46 AM
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Well, that's my fault for trusting Taco. I spoke with Taco customer service to ask them what the replacement vent part number was for the VRTX123-5 and they said get the 419, which is the high pressure vent. Looking at my current Taco unit, it is the VRTX123-5 model but the vent says 150psi at 240F, whereas the 419 vent I just bought with the new unit says 250psi at 240F. I'd really like to solve the problem as quickly as possible. Would there be any reason why I couldn't use the high pressure vent, or should I send back for a replacement?
 
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Old 10-16-12, 07:25 AM
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Personally if it were myself, and the fact that we are on a fixed income, I would send that back and simply get the maid o mist 75 or the taco 418-4.

As quickly as possible would be to call your local furguson and see if they have in stock. They sell to the public.

Simply input your zip code here.

Locations Finder
 
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Old 10-16-12, 10:36 AM
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I hear ya, and money is a concern, but my wife and I have a bunch of family staying the weekend to see our new house and I'd rather fix the problem now.

In comparing the specs for both vents, it looks like the only differences are in the "Max Pressure" and "Max Venting Pressure." I don't mind if the 419 vent is stronger than needed but what I'm worried about is if the max venting pressure means that it won't work properly with a regular household setup like I have. Money concerns aside, do you think the high pressure 419 vent will still work fine?
 
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Old 10-16-12, 03:46 PM
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Yes, the 419 will work fine.

Once you get the vent working, if you are lucky the air in the system will slowly be removed automatically as it runs. You should start to hear less and less noise over the following days/weeks.

I want to clarify something though... when you remove the old vent, you are going to have water coming out, even if you let the pressure off the boiler. You want to let as little of the old water out as possible because adding fresh water will only compound the problem of air in the system.

So, before you let the pressure off on the boiler, close all of those yellow handled ball valves in order to isolate the zones and the water heater.

Then open a drain on the boiler and drop the pressure to zero.

Find a bucket or dishpan or something that will fit under the vent to catch the water.

Probably a good idea to cover electric controls with plastic to prevent water getting into them.

Have the new vent ready to go back in because you are going to want to work quickly...

Start unscrewing the vent to get an idea of how much water will come out. If it's a LOT, you might need to drain a little water from the boiler to below the level that you are working... it won't be all that much because you have all the yellow valves closed... a gallon or two maybe...

But, if you have the new vent ready to go back on, you may be able to work real quicks like and pull the old and slap in the new without making a watery mess.
 
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Old 11-02-12, 12:04 PM
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Sorry for the delayed response, a lot has happened since my last update. I ended up having a plumber check out the system in person because he owed me a favor. We replaced the backflow preventer, pressure regulator, and expansion tank, all of which he said were toast. We bled the system and all works well, except the Taco hy-vent still needs to be replaced.

The problem is it won't unscrew from the air separator. Using a monkey wrench, he tried to unscrew the hy-vent and it would not budge and he eventually had to stop because he was afraid of breaking it. We did use some penetrating lubricant to try and free it but that did not work.

Any tips on unscrewing the hy-vent from the Taco air separator?
 
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Old 11-28-12, 06:01 AM
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I just wanted to follow-up and say thanks for all the help. We ended up unscrewing the new Taco air separator in half and swapping hy-vents that way. I have the new expansion tank hung vertically too and supported, like NJ Trooper suggested. The system is working flawlessly and I really appreciate the spot-on advice from you guys.
 
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Old 11-28-12, 04:30 PM
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Yer quite welcome!

Thanks for stopping back and letting us know.
 
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